Carbyne Ring Activated Using ZnCl₂ for Hydrogen Adsorption: DFT Study

Area of Science:

• Materials Science
• Computational Chemistry
• Energy Storage

Background:

• Hydrogen is a clean energy carrier, but efficient storage remains a challenge.
• Carbyne, a one-dimensional carbon allotrope, has been explored for various applications.
• Chemical activation and functionalization are key strategies to enhance material properties.

Purpose of the Study:

• To investigate the feasibility of activated carbyne as a hydrogen storage material.
• To explore calcium (Ca) sorption on activated carbyne and its interaction with hydrogen (H₂).
• To evaluate the hydrogen storage capacity and stability of Ca-decorated carbyne systems.

Main Methods:

• Density Functional Theory (DFT) simulations were employed.
• Van der Waals interactions were considered for accurate modeling.
• Calculations included chemical activation with zinc dichloride (ZnCl₂), Ca sorption, H₂ adsorption, adsorption isotherms, and molecular dynamics simulations.

Main Results:

• Chemical activation with ZnCl₂ increased the carbyne surface area by 5.17%.
• Calcium atoms donated electrons to the carbyne ring, enhancing hydrogen sorption by 21.8%.
• Ca-decorated carbyne achieved a theoretical uptake of 13.8 wt % (Ca₃C₁₂-21H₂ system), exceeding the DOE target, with favorable adsorption energies (0.3-0.5 eV/H₂) for charge/discharge cycles.

Conclusions:

• Activated carbyne functionalized with calcium is a promising material for hydrogen storage.
• The Ca-decorated C₁₂-ring systems exhibit high theoretical hydrogen uptake and good thermal stability.
• The calculated equilibrium pressures and desorption temperatures suggest practical applicability for hydrogen storage.